Cardiff will be home to Reading, who are one of five teams alongside Bolton, Burton, Barnsley and Birmingham struggling to avoid two remaining relegation places alongside Sunderland.
On Saturday, two goals from skipper Sean Morrison gave Cardiff a 2-0 win at Hull City to keep manager Neil Warnock on course for a record eighth promotion.
The second-placed Bluebirds are one point ahead of Fulham, who are the only team able to deny them promotion alongside Wolverhampton Wanderers, who drew 0-0 with Sheffield Wednesday.
Aston Villa must be content with a playoff place after drawing 1-1 with Derby County.
Middlesbrough clinched their own playoff spot with a 2-0 win over Millwall, who would need freak results next week to join them in the promotion shootout.
Derby effectively need just a point from next week's visit of Barnsley to secure the fourth playoff spot although Preston North End, who trail Gary Rowett's side by two points, could profit from any slip up after beating Sheffield United 1-0.
That result ended the Blades' own hopes, with Brentford, 2-0 losers at Barnsley, also dropping out of the running.
(Reporting by Neil Robinson; Editing by Christian Radnedge)
